Reinforced wire brush or wheel



Jan- 8, 1963 w. A. HARTZ ETAL REINEoRcED wIEE BRUSH on WHEEL Filed Aug. 26, 1959 INVENTORS VVlter Hartz M ichael [Calla/ur ,M1- ATTORNEYS 'lates or the like in the polyester resin.

United States Patent Otice 3,0%,705 Fatenteri Jan. 8, 1963 3,071,795 REINFORCED WIRE BRUSH @R Walter A. Hartz and Michael Kallaur, Cuyahoga Falls, Ohio, assgners to The General Tire @t Rubber Cornpany, Akron, Ohio, a corporation of @hier Filed Aug. 26, 1959, SenNo. 836,294 9 Claims. (Cl. 15-198) The present invention relates to improvements in metal brushes such as are used for polishing and cleaning of metal and other articles, and more particularly to improved wire brushes and methods of preparing the same.

Heretofore, wire brushes have been embedded in plastic to reinforce the bristles, to protect the bristles, and to improve the action of the polishing wheel as disclosed, for example, in United States Patent No. 2,648,084, but such plastic-reinforced wire brushes have been subject to surface hardening and reduction in flexibility which shortened the life and reduced the polishing efficiency.

We have `discovered that ,such surface hardening can be avoided by employing certain unsaturated metallo-organic compounds, such as dialkyl tin or lead maleates or fumer- The useful life of a wheel comprising wire bristles embedded in polyesterolefins is increased greatly when the polyester-olens are mixed with dibutyl tin maleate, for example. Further improvement can be obtained by employing acrylonitrile or by using cellulose fibers as a filler. Advantages may also be obtained by including abrasive materials in the polymeric material or by covering the opposite faces of each bristle section with fabric.

An object of the present invention is to reduce surface hardening and loss of flexibility in a polyester-resin reinforced polishing wheel.

Other objects of the invention are to provide a simple inexpensive polishing wheel which has improved polishing characteristics, and to increase the durability and useful life of reinforced rotary wire brushes.

Other objects, uses, and advantages of the present invention will become apparent to those skilled in the art from the following description and claims and from the drawings in which:

FIGURE 1 is a top plan view on a reduced scale of a mold containing a wire brush embodying the present invention;

FIGURE 2 is a Vertical sectional View taken on the line 2 2 of FIG. 1 and on the same scale;

FIGURE 3 is a fragmentary plan viewon a reduced scale of a portion of a brush embodying the present invention; and

FIGURE 4 is a fragmentary vertical sectional View taken on the line 4 4 of FIG. 3 and on a larger scale.

Referring more particularly to the drawings in which like parts are identified by the same numerals throughout the several views, FIGURES 3 and 4 show a brush l0 comprising a hub portion 1 having a shaft-receiving opening 2 and a series of locking rings 3 for retaining the wire bristles 4 on the hub. The bristles extend radially outwardly from the hub portion 1, butit will be understood that the arrangement of the bristles and the shape of the polishing wheel may be varied considerably. The spaces 5 between the bristles 4 are filled with a solid polymerization product, such as a polyester resin composition of the type described herein. Such resin is solidified in situ by molecular growth or by polymerization so as to enclose all but the end portions of the various wire filaments or bristles.

FIGURES l and2 show a mold 11 which may be used to manufacture wire brushes or polishing wheels according to the present invention. This mold has a cavity adapted to receive conventional wire brushes and of such size that the bristles bear against the wall of the cavity. As herein shown, the mold has a lower portion 13, a cover 14 and means for fastening the cover i4 to the lower portion of the mold including lugs 15 and nuts 16. A suitable gasket 17 is applied on each side of the surface of the hub to form a seal which prevents liquid from entering into the shaft-receiving opening 2. Means are provided for applying pressure to seal the space between the exterior surface of the hub 1 and the parts of the mold, including spaced collars 1S and bolt 19. The polymerizable composition may be poured through an opening 20 into the mold so as to surround and envelop all of the bristles, a Vent 21 being provided to permit escape of air from `the mold.

Excellent reinforced wire brushes may be made in accordance with the present invention by embedding the bristle portion of a wire brush in a solid matrix comprising a rubbery copolymer of linear polyesters. These linear polyesters usually comprise (a) a polyhydric alcohol, preferably a dihydric alcohol, such as ethylene glycol,

.diand tri-ethylene glycols, or the like, and (b) a mixture of at least one saturated dibasic acid and at least one unsaturated dibasic acid.

The saturated dibasic acid is preferably any dicarboxylic acid of suiiicient number of carbon atoms to prevent formation with the dihydric alcohols of a five, six or seven-numbered ring and usually has at least four carbon atoms. Examples of such acids are adipic acid, sebacic acid, phthalic acid, terephthalic acid, etc., although any dicarboxylic acid may be used providing the alcohols are chosen to prevent ring formation. The saturated acids generally comprise a major proportion of the acidic material. The unsaturated dibasic acids, of which maleic and fumarie acids are examples, comprise generally a minor portion of'the composition and are present primarily to provide crosslinking points for polymerization vwith the styrene, acrylonitrile or other compatible monoolefin. About 5 to 19 mols of saturated acids should be used per mol of unsaturated acid.

The polyester components are usually prepared by first condensing a polyhydric alcohol and a mixture of dibasic acids, or their anhydrides, to form a liquid-to-viscous syrupy polyester which is preferably largely of linear nature. This polyester is generally condensed by stirring the mixture of reactants containing preferably a slight excess of polyhydric alcohol while heated to boiling until the boiling point of the reactants becomes well over 200 C., where it is evident that most of the water formed by the condensation reaction is removed as soon as it is formed. The container in which the esterification reaction generally occurs is fitted with a suitable reux condenser which operates at a sufficiently high temperature to condense only the organic constituents and to permit the escape of water vapor. The molecular weight of the polyester thus obtained is determined largely by the proportion of the reactants, the highest molecular weight being obtained with an exact balance of hydroxyl and carboxyl groups.

In place of part or even all of the polyhydric alcohols and polybasic acids, a hydroxy carboxylic acid having suflicient space between the carboxyl and hydroxyl groups to prevent forma-tion of live, six or seven-numbered rings may be condensed alone, providing a small amount of unsaturated linkages are provided, either by mixture of a small amount of unsaturated acid with dihydric alcohol or by the use of suitable unsaturated hydroxy aliphatic acids.

The polyester is mixed with the mono-oleiinic monomers, such as styrene and acrylonitrile, the amount by weight of styrene preferably being at least twice the amount of acrylonitrile. An amount of styrene equal to o1 at least 20% by weight and no more than 55% by weight of the total amount of polyester, acrylonitrile and styrene provides satisfactory results. it is preferable to employ an amount by weight of acrylonitrile equal to 5 to by weight of the total amount of polyester, styrene and acrylonitrile and an amount by weight of stvrene plus acrylonitrile equal to 25 to 60% by weight of said total amount. Generally an amount of polyester equal to more than 50% of said total amount is preferred. The amount of unsaturated dibasic acid may be as high as mol percent or more of the polyester, (excluding mono-olefinic component), but about 2 to 12 mol percent is preferred.

It will be understood that mixtures of polyhydric alcohols, such as ethylene glycol and/ or glycerol with a polyethylene glycol may be used in place of one polyhydric alcohol alone, and a single dicarboxylic acid or a mixture of several, may be used providing the acrylonitrile is compatible with the resultant liquid or viscous condensation product.

For some reason which is not understood completely, an encapsulated plastic-reinforced wire brush is improved greatly by incorporating, with each 100 parts by weight of the polyester-monooletin mixture, 0.3 to 3.0 parts of an unsaturated metallo-organic compound, such as a diallyl tin maleate or fumarate having 2 to 20 carbon atoms in each alkyl group, the corresponding dialkyl lead maleate or fumarate or tribasic lead maleate. Excellent results may be obtained if such compound is dibutyl tin maieate or fumarate, dioctyl tin maleate or fumarate, dihexyl tin maleate or furnarate or the like. Good results may be also obtained with other maleates and fumarates such as diethyl tin maleate, dibutyl lead maleate, dibutyl lead fumarate, dioctyl lead maleate, dihexyl lead maleate, or other dialkyl metal salts of unsaturated dicarboxylic acids wherein each alkyl group has 2 to 20 carbon atoms.

Tribasic lead maleate has a structural formula as follows:

The use of small amounts of such unsaturated metalloorganic compounds in the polyester-monomer mixture for some unknown reason improves the resistance of the polishing wheel to surface hardening where the wheel is subjected to relatively light loads (for example in the neighborhood of 1000 grams). Similar polishing Wheels made without such metallo-organic compounds experience surface hardening if subiected to such light loads and permitted to cool periodically, with the result that the iiexibility and useful life of the wheel are reduced. The present invention provides a method of avoiding this diiculty.

The polyester-encapsulated rotary wire brushes of this invention are preferably provided with l to parts of 'orous fillers and/or l to 50 parts of mineral fillers per 100 parts by weight of polymerizable material (polyestermonomer mixture). The fibrous fillers include natural fibers such as wool and silk; inorganic fibers, such as asbestos and fiber glass; and synthetic fibers such as nylon, Orion, rayon and Saran. Suitable mineral fillers include calcium carbonate, aluminum silicate (clays), mica, silica and silicon carbide. r`he amount of fillers is selected so as to give a pourable mix having the properties needed for a polishing wheel. Best results are obtained using a mixture of mineral and fibrous fillers including alpha cellulose or finely divided wood cellulose having a particle size of 1 to 100 microns. A wood cellulose such as Solltet-Floc having a particle size of to 90 microns provides a plastic material having exceptional uniformity and consistency. Good results can be obtained, for example, using a mixture of l to 20 parts of clay filler and 5 to 20 parts of Sellia-Floc per 100 parts of polymerizable mixture.

Example l Fifty parts by weight of a polyester resin made by reacting 1 mol of maleic anhydride, 4 mols of phthalic anhydride, 5 mols of sebacic acid and 10.1 mols of diethylene glycol are intimately mixed with 42.5 parts of styrene, 7.5 parts of acrylonitrile, 2.15 parts of a catalyst (50% benzoyl peroxide in tricresyl phosphate), 10.0 parts of Sollta-Floc having a particle size of 35 to 90 microns, 7.5 parts of clay filler, and 1.0 part of dibutyl tin maleate.

The above materials are then deaerated under vacuum and 35 grams thereof are poured into a mold cavity having a diameter of about 3 inches and a depth of about 5//16 inch. A wire brush of the type shown in the drawings having a diameter of about 3 inches is positioned in the mold, a cover plate is attached, and the entire assembly is then placed in a conventional hydraulic press hvaing its platens heated to 275 F. The press is closed to contact pressure for 10 minutes and is then opened to remove the completed encapsulated wire brush or polishing wheel. The polishing wheel is then cooled to room temperature.

The resulting polishing wheel will operate in excess of 10 huors when operated periodically at 3600 r.p.m. against a stationary test bar with a 1000 gram load whereas a similar wheel made without dialkyl tin maleate or similar material will lose its flexibility rapidly due to surface hardening and will as a result have a much shorter useful life when subjected to the same conditions.

Example Il A polyester resin is prepared by reacting maleic anhydride, phthalic anhydride, sebacic acid and diethylene glycol as in Example I. Fifty parts by weight of this resin are intimately mixed with 40 parts of styrene, 8 parts of acrylonitrile, 2.15 parts of a catalyst (50% benzoyl peroxide in tricresyl phosphate), 9 parts of Sellia-Floc having a particle size of 35 to 90 microns, l0 parts of aluminum silicate, and 0.9 part of tribasic lead maleate.

The above materials are then deaerated, poured into the mold cavity over the wire brush, and the mold heated to produce an encapsulated wire brush or polishing wheel as in Example I.

Again, the polishing wheel has little tendency for surface hardening and has a long useful life.

Example lll A liquid polyester is prepared by heating 1.05 mols of diethylene glycol with 0.2 mol of maleic anhydride and 0.8 mol of adipic acid. The mixture is heated while stirring in a vessel equipped with a redux condenser, said condenser being cooled by fluid maintained at a temperature of about C. and being arranged to permit escape of water vapor but to return higher boiling constituents to the reaction mixture. Heating is continued to maintain boiling conditions until the temperature reaches 225 C. whereupon the reaction mixture is allowed to cool. About 40 parts by weight of the cooled reaction mixture is mixed with 32 parts of styrene, 13

fparts of aerylonitrile, 10 parts of Solka-Floc having a particle size of 35 to 90 microns, 5 parts of clay iiller, 0.1 part of dibutyl tin maleate, and 2.0 parts of a catalyst (50% benzoyl peroxide in tricresyl phosphate).

A wire brush having bristles extending radially from its hub is incorporated in the cavity of the mold 11 so as to rest on the inner mold surface 25, said mold surface having been previously coated with a layer of any suitable mold lubricant (eg. silicone, carnauba waxes, microcrystalline waxes, etc.). In the mold the hub 1 bears against the gasket 17 and the external edges 26 of the bristles bear against the portion 25a of the inner mold surface 25. The fluid solidifiable composition mixed as indicated above is poured while in the liquid state through the opening 20 until it rises within the vent 21, and it is allowed to remain in the mold at 60 C. until it has completely solidified. The completed polishing wheel or `brush is then removed from the mold and is mounted on a driven shaft for use in polishing or cleaning metal. It is found that the useful life of such polishing wheel is several times that of similar Wheels as described, for example, in United States Patent No. 2,648,084 when operated periodically at alight load such as 1000 grams.

The present invention greatly increases the life and cutting ability of encapsulated wire brushes without appreciably eiecting the ability of the brush to adapt to complex surfaces. The major portion of this improvement is due to the reduction in the tendency for the plastic to harden in use. The polishing wheels made by the present invention avoid excessive powdering and unsightly smearing of surfaces. These results are obtained when polymerizing polyester with styrene and acrylonitrile in admixture with dibutyl tin maleate or fumarate or similar lead or tin salts of the type described herein.

Wherever used in the specification or claims, the term parts means parts by weight.

It will be understood that the above description is by way of illustration rather .than limitation and that in accordance with the patent statutes, variations and modilications of the specific methods and articles disclosed herein may be made without departing from the spirit of the invention.

Having described our invention, we claim:

1. In a wire brush comprising a fastening portion and a plurality of wire bristles extending therefrom, a solid rubbery material substantially completely surrounding and reinforcing the sides of said wire bristles and joining portions spaced from said fastening portion together, said material benig a solid polymerization product of a polyester -of at least one polyhydric alcohol, at least one compound selected -from the group consisting of dicarboxylic acids and dicarboxylic acid anhydrides, and a monoolenic compound compatible and polymerizable therewith, said material including about 0.3 to 3% by weight of an unsaturated dialkyl metal salt of a mono-unsaturated dicarboxylic acid, each alkyl group of said salt having two to twenty carbon atoms, the metal of said salt being selected from the group consisting of lead and tin.

2. In a wire brush comprising a fastening portion and a plurality of wire bristles extending therefrom, a solid rubbery material substantially completely surrounding and reinforcing the sides of said wire bristles and joining portions spaced from said fastening portion together, said material being a solid polymerization product of a polyester of at least one polyhydric alcohol, at least one compound selected from the group consisting of dicarboxylic acids and dicarboxylic acid anhydrides, and a mono-olefinic compound compatible and polymerizable therewith, said material including about 0.3 to 3% by weight of tribasic lead maleate.

3. A combination as deiined in claim 1 wherein said metal salt is an unsaturated dialkyl tin salt of a monounsaturated dicarboxylic acid having 4 carbon atoms, each alkyl group having l2 to 20 carbon atoms.

4. A combination as defined in claim 1 wherein said metal salt is an unsautrated dialkyl lead salt of a monounsaturated dicarboxylic acid having 4 carbon atoms, each alkyl group having 2 to 20 carbon atoms.

5. A combination as defined in claim 3 wherein said metal salt is dialkyl tin maleate.

6. A combination as dened in claim 4 wherein said metal salt is dialkyl lead maleat.

7. A combination as defined in claim 1 wherein said metal salt is dibutyl tin maleate.

8. The combination defined in claim 1 wherein 100 parts of said polymerization product contains 1 to 25 parts of wood cellulose with an average particle size of 1 to microns.

9. In a wire brush comprising a fastening portion and a plurality of wire bristles extending therefrom, a solid rubbery material substantially completely surrounding and reinforcing the sides of said wire bristles and joining portions spaced from said fastening portion together, said material being a solid polymerization product of acrylonitrile, a polyester of at least one polyhydric alcohol and at least one compound selected from the group consisting of dicarboxylic acids and dicarboxylic acid anhydrides, anda mono-olefinic compound compatible with said poly ester, the amount by weight of acrylonitrile being equal to about 5 to 15% of the total amount of said polyester, acrylonitrile and said mono-olefinic compound, said material including 0.3 to 3% by weight of a dialkyl tin salt of a mono-unsaturated dicarboxylic acid having 4 carbon atoms.

Offenbach et al., v1956, volume ll, Journal of Colloid Science (pp. 39-47), p. 39 relied on). 

1. IN A WIRE BRUSH COMPRISING A FASTENING PORTION AND A PLURALITY OF WIRE BRISTLES EXTENDING THEREFROM, A SOLID RUBBERY MATERIAL SUBSTANTIALLY COMPLETELY SURROUNDING AND REINFORCING THE SIDES OF SAID WIRE BRISTLES AND JOINING PORTIONS SPACED FROM SAID FASTENING PORTION TOGETHER, SAID MATERIAL BEING A SOLID POLYMERIZATION PRODUCT OF A POLYESTER OF AT LEAST ONE POLYHYDRIC ALCOHOL, AT LEAST ONE COMPOUND SELECTED FROM THE GROUP CONSISTING OF DICARBOXYLIC ACIDS AND DICARBOXYLIC ACID ANHYDRIDES, AND A MONOOLEFINIC COMPOUND COMPATIBLE AND POLYMERIZABLE THEREWITH, SAID MATERIAL INCLUDING ABOUT 0.3 TO 3% BY WEIGHT OF AN UNSATURATED DIALKYL METAL SALT OF A MONO-UNSATURATED DICARBOXYLIC ACID, EACH ALKYL GROUP OF SAID SALT HAVING TWO TO TWENTY CARBON ATOMS, THE METAL OF SAID SALT BEING SELECTED FROM THE GROUP CONSISTING OF LEAD AND TIN. 